Electric switch



A. CIANCHI ELECTRIC SWITCH June 13, 1939.

Filed Nov. 5, 1937 Patented June 13, 1939 ELECTRIC SWITCH AlfredoCianchi, London, England Application November 5, 1937, Serial No.173,031 In Great Britain November '7, 1936 12 Claims.

This invention relates to electric switches' comprising a vesselenclosing a plunger which is acted upon by magnetic means to cause it tomove and establish or disestablish electrical connection betweenelectrodes passing through the wall of the vessel. Connection may beestablished or disestablished by means of solid contacts one or both ofwhich is or are moved by the plunger, or by way of mercury or otherconducting liquid.

According to the invention the plunger is wholly or partly guided sothat it moves clear of the wall of the vessel by one or more guideswhich extend in the direction of movement of the plunger. I prefer toarrange this guide or these guides in line with the central axis ofmovement of the plunger although a similar result may be obtained if itor they is or are offset from its axis. The invention may includefurther features which are hereinafter referred to and claimed.

It will now be described with reference to the accompanying diagrammaticdrawing which illustrates by way of example a number of switchesembodying it. In the drawing Figures l to 4 are longitudinal sectionalviews of four mercury switches provided with different forms of plungerguide,

Figure 5 is a perspective view of a modified form of guide,

Figures 6 and 7 are longitudinal sectional views of another form ofmercury switch and of a solid-contact switch respectively provided witha plunger guide according to the invention.

In all the figures of the drawing except Figure 5, I is the vessel ofthe switch, 2 and 3 are the electrodes which pass through its wall inwhich they are fused, 4 is the plunger and 6 the electromagnetic meansoperating it. The switches of Figures 1 to 4. are mercury switches, theplunger in each case consisting of a tubular member 4 of glass, quartz,porcelain, steatite, or other spark-resisting material which is providedat its upper end with a magnetic armature 5 in the form of a length ofiron tube fitting closely on the outside of the tubular plunger near thetop. The plunger has a closed lower end forming a cup vcontaining aquantity of mercury 1 and the plunger 4 with the mercury 1 in itnormally floats on a main body of mercury 8 in the lower part of theswitch vessel I. The upper electrode 2 passes down the inside of thetubular plunger 4 and coaxially with it and dips into the pool ofmercury 1. The lower electrode 3 projects into the body of mercury 8 inwhich it is continuously immersed. At a point displaced from its lowerend the plunger has an opening 9 so that when the plunger is drawn downin the mercury 8 on energising of the solenoid 6, mercury from 8 passesthrough the opening 9 into the pool 1 so as to establish electricalconnection between the electrodes 2 and 3. When the solenoid isde-energised the plunger 4 rises due to its buoyancy and the two bodiesof mercury are separated at the opening 9 so as to disestablishelectrical connection between the electrodes 2 and 3. In the switch ofFigure 1 the plunger 5 is guided solely on the upper electrode` 2 whichpasses through two spaced constrictions on the plunger 4. The upperconstriction is formed by turning in the upper end of the tube, forexample after fusing it, and as indicated at III. rPhe secondconstriction is formed by making a neck II in the plunger 4 at a pointdisplaced suiliciently far from I0 to ensure that the plunger 4 isadequately guided by the electrode 2 so that it moves freely up and downin the direction of its longitudinal the wall of the vessel I.

tions are described as ing parts of the plunger 4, it is that when theterm axis without touching Although the constricbeing formed by deformtobe understood constriction is employed,

it is intended to cover also the insertion in the plunger of separatemembers having apertures substantially fitting the electrode. providedto enable Openings are mercury which may have got into the plunger abovethe lower constriction to escape easily.

In the switch of Figure 2 the upper end of the plunger is guided on theelectrode 2 by a constriction I0 in a similar way to that adopted in theswitch of Figure l. plunger, however, jection I2 which on a member I3lower electrode The lower end of the is provided with a coaxialpropasses into an opening or eye secured to the upper end of the 3. Hereagain the guides 2 and I2 guide the plunger 4 and armature 5 so thatthey move up and down without touching the walls of the vessel.

Naturally the eye could be on the end of a member mounted on the plungeras by being fused into it instead of on the electrode and the electrodearranged to enter the eye; or the electrode could pass directly into acoaxial opening in the plunger.

In the switch of plunger is guided in Figure 3 the lower end of the thesame way that the lower end of the plunger of Figure 2 is guided, butthe upper end is guided by plunger itself. shown as being projections I4on the The upper edge of the plunger is turned outwards for this purposeand a continuous ring formed in this way or otherwise may be employed,but it is preferred to interrupt the ring so that the plunger engageswith the wall at a number of separate points disposed around its axisand preferably three. The projections could be formed on a separatemember tted to the plunger or formed by bending outwards parts of thearmature 5.

The switch of Figure 4 is similar to the switch of Figure 2 except thatthe guide I2, instead of passing through a member I3 carried on the endof the electrode 3, passes through a member I3 carried on the switchvessel I from the wall of which it is spaced by radial arms so as toallow free passage of mercury to the electrode 3. Instead of using alower guide such as that of Figure 2, the lower end of the electrode Icould be provided with an enlargement or a spider or other projectionengaging the inner wall of the tubular plunger near the bottom, theinner` wall then being made parallel-sided at least for a lengthcorresponding to the distance through which the plunger moves. The lowerpart of such an electrode is illustrated in perspective in Figure 5, thelower end in this case being provided with a three-armed plunger,A theend surfaces of which come into/contact with the inner wall of theplunger to guide it. If desired, of course, two spaced spiders or otherenlargements or projections could be provided on the electrode to engagethe inner wall of the plunger at two spaced points. It would not then benecessary to provide any other guide for the plunger.

Figure 6 illustrates a form of mercury switch which diiers from that ofFigures l to 4. The switch of Figure 6 is similar to the ordinary typeof plunger mercury switch in which contact is made or broken merely bydisplacing the level of a body of mercury as a result of Varying theextent of immersion in it of a plunger in the form of an open-endedtube. Such a plunger could be employed in the present case and be guidedby an upper electrode 2 provided with spaced spiders such as thoseillustrated in Figure-5. In the switch of Figure 6, however, the plungeris in the form of a length of glass or like tube, the two ends of whichare turned inwards to. form two constrictions which slide up and down onthe upper electrode 2. The plunger is provided with an armaturev 5 in asimilar way to the plungers of Figures l to 4. 'Ihe electrode 3 of theswitch of Figure 6 is in a side limb of the main switch vessel intowhich mercury iiows to establish connection between the electrodes 2 and3 when the plunger is drawn down to raise the level of mercury.

Ihe switch of Figure 7 is a switch in which connection is made andbroken between solid contacts. The contacts are indicated at I5 and IB,both being spring. contacts connected respectively to the electrodes 2and 3. Contact I5 is ixed while the Contact I6 is mounted on the plunger4- which is moved by magnetic means by way of an armature 5 as in thecase of the other switches described above. The plunger 4 is normallypulled in such a direction that the contacts I5 and I 6 are separatedbut is moved against the action of the spring I1 to cause the contactsto interengage and establish connection between the electrodes 2 and 3when the solenoid is energised. As soon as it is de-energised the springpulls the plunger back to disengage the contacts. The plunger is guidedon the electrode 2 in one of the ways described above so that it movesclear of the walls of the vessel l.

It will be understood that in all cases the area of contact between theplunger 4 and the guide or guides is made as small as is reasonablypossible so as to enable the plunger to move freely.

In the case of the mercury switches described above it will be noticedthat the clearance between the armature 5 and the wall of the vessel Iis less than that between the lower part of the plunger where it entersthe mercury. It is, of course, desirable for the armature to be as nearthe wall as possible for magnetic reasons, but if the plunger Were madeonly the same distance from the wall of the vessel, diculty would beexperienced with the mercury which would not then be likely to rise andfall freely or else undue friction would be caused. If necessary thelower part of the plunger may be made of smaller diameter than the upperpart so as to obtain a still greater clearance at the part where it isimmersed in the mercury. The part of the plunger that enters the mercuryis also made smooth and of a tapered, rounded or other shape that offersa low resistance to movement of the plunger in the mercury, and for thesame reason projections of substantial area on the part of the plungerthat enters the mercury are avoided. Thus, in the arrangement of Figure3, although projections I4 are employed they are employed on the part ofthe plunger that does not enter the mercury. By employing guiding meansaccording to the invention, and possibly also one or other of theexpedients just described, it is possible to make a switch which willoperate with a low consumption of current if it is operatedelectromagnetically. The switch be a movable magnet required to move thespondingly low.

I claim:

l. An electric switch comprising a vessel containing a body ofconducting liquid, a movable plunger in said vessel containing aconducting liquid, an electrode passing through the wall of the vesselinto said first body of conducting liquid, a second electrode passingthrough the wall of the vessel into said second body of conductingliquid, magnetic means for actuating said plunger to vary the extent ofimmersion thereof in said rst body of conducting liquid selectively inwhich case the energy magnet would be correto establish and breakelectrical contact between` Y said electrodes, and a. plurality ofguiding means disposed at points spaced longitudinally in the directionof movement of said plunger within said vessel for guiding said plungerclear o1" the wall of said vessel, with at means associated with saidvessel and extending in the direction of movement of said plunger.

2. An electric switch comprising a vessel containing a body ofconducting liquid, a movable plunger in said vessel containing liquid,an electrode passing through the wall of the vessel into said rst bodyof conducting liquid, a second electrode passing through the wall of thevessel into said second body of conducting liquid, magnetic means foractuating said plunger to vary the extent of immersion thereof in saidrst body of conducting liquid selectively to establish and breakelectrical contact between said electrodes, and a plurality of guidingmeans disposed at points spaced longitudinally in the direction ofmovement of said plunger within said vessel for guiding said plungerclear of the wall of said vessel, with at least one of said guidingmeans mounted on said vessel and extending in the direction of movementof said plunger.

could, however, if desired least one of said guiding i a conductingv 3.An electric switch comprising a vessel containing a body of conductingliquid, a movable plunger in said vessel containing a conducting liquid,an electrode passing through the wall of the vessel into said first bodyof conducting liquid, a second electrode passing through the wall of thevessel into said second body of conducting liquid, magnetic means foractuating said plunger to vary the extent of immersion thereof in saidrst body of conducting liquid selectively to establish and breakelectrical contact between said electrodes, and a plurality of guidingmeans disposed at points spaced longitudinally in the direction ofmovement of said plunger within said vessel for guiding said plungerclear of the wall of said vessel, with at least one of said guidingmeans mounted on said plunger and extending in the direction of movementthereof and cooperating with a guide member on said vessel.

4. An electric switch comprising a vessel containing a body ofconducting liquid, a movable plunger in said vessel containing aconducting liquid, an electrode passing through the wall of the vesselinto said first body of conducting liquid, a second electrode passingthrough the wall of the vessel into said second body of conductingliquid, magnetic means for actuating said plunger to vary the extent ofimmersion thereof in said rst body of conducting liquid selectively toestablish and break electrical contact between said electrodes, and aplurality of guiding means disposd at points spaced longitudinally inthe direction of movement of said plunger within said vessel for guidingsaid plunger clear of the wall of said vessel, with one of said guidingmeans mounted on said vessel and extending in the direction of movementof said plunger and the other of said guiding means being formed on saidplunger extending in the direction of movement thereof and cooperatingwith a guide member on said vessel.

5. An electric switch comprising a vessel containing a body ofconducting liquid, a tubular plunger in said vessel containing aconducting liquid and movable in the direction of its longitudinal axis,an electrode passing through the wall of the vessel into said rst bodyof conducting liquid, a second electrode passing through the wall of thevessel into said second body of conducting liquid, magnetic means foractuating said plunger to vary the extent of immersion thereof in saidfirst body of conducting liquid selectively to establish and breakelectrical contact between said electrodes, and a plurality of guidingmeans disposed at points spaced longitudinally in the direction ofmovement of said plunger within said vessel for guiding said plungerclear of the wall of said vessel with at least one of said guiding meanscomprising a guide member mounted on said vessel, extending in thedirection of movement of said tubular plunger and passing thereinto, anda constriction pressed on said plunger adapted to slide on the guidemember as the plunger moves.

6. An electric switch comprising a vessel containing a body ofconducting liquid, a tubular plunger in said vessel containing aconducting liquid and movable in the direction of its longitudinal axis,an electrode passing through the wall of the vessel into said first bodyof conducting liquid, a second electrode passing through the wall of thevessel into said second body of conducting liquid, magnetic means foractuating said plunger to vary the extent of immersion thereof in saidrst body of conducting liquid selectively to establish and breakelectrical contact between said electrodes, and a plurality of guidingmeans disposed at points spaced longitudinally in the direction ofmovement of said plunger within said vessel for guiding said plungerclear of the wall of said vessel, said guiding means comprising a guidemember mounted on said vessel, extending in the direction of movement ofsaid tubular plunger and passing thereinto, and spaced constrictionsformed on said plunger adapted to slide on the guide membei` as theplunger moves.

7. An electric switch comprising a vessel containing a body of'conducting liquid, a tubular plunger in said vessel containing aconducting liquid and movable in the direction of its longitudinal axis,an electrode passing through the l wail of the vessel into said rst bodyof conducting liquid, a second electrode passing through the Wall of thevessel into said second body of conducting liquid, magnetic means foractuating said plunger to vary the extent of immersion thereof in saidfirst body of conducting liquid selectively to establish and breakelectrical contact between said electrodes,v and a plurality of guidingmeans disposed at points spaced longitudinally in the direction ofmovement of said plunger within said vessel for guiding said plungerclear of the wall of said vessel, said guiding means comprising on saidvessel, extending in the direction of movement of said tubular plungerand passing thereinto, said guide member being provided with lateralprojections engaging with the inner wall of said tubular plunger andadapted to be guided thereby.

8. An electric switch comprising a vessel containing a body ofconducting liquid, a tubular plunger in said vessel containing aconducting liquid and movable in the direction of its longitudinal axis,an electrode passing through the wall of the vessel into said first bodyof conducting liquid, a second electrode passing through the wall of thevessel into said second body of conducting liquid, magnetic means foractuating said plunger to vary the extent of immersion thereof in saidfirst body of conducting liquid selectively to establish and breakelectrical contact between said electrodes, and a plurality of guidingmeans disposed at points spaced longitudinally in the direction ofmovement of said plunger within said vessel for guiding said plungerclear of the wall of said vessel, one of said guiding means comprising aguide member mounted on said plunger and. provided with lateralprojections engaging the inner wall of said vessel above the level ofthe bodies of conducting liquid therein.

9. An electric switch according to claim 1, wherein at least one of theelectrodes forms a part of the guiding means.

10. An electric switch according to claim 5 wherein one of saidelectrodes constitutes said guide member.

11. An electric switch comprising a vessel containing a body ofconducting liquid, a tubular plunger in said Vessel containing aconducting liquid and movable in the direction of its longitudinal axis,an aramture of magnetic material mounted on the upper end of saidplunger, an electrode passing through the wall of the vessel into saidrst body of conducting liquid, a second electrode passing through thewall of the vessel into said second body of conducting liquid, magneticmeans cooperating with said armature for actuating said plunger to varythe extent of ima guide member mounted mersion thereof in said rst bodyof conducting liquid selectively to establish and break electricalcontact between said electrodes, and a plurality of guiding meansdisposed at points spaced longitudinally in the direction of movement ofsaid plunger within said vessel for guiding said plunger clear of thewall of said vessel, with at least one of said guiding means associatedwith said vessel and extending in the direction of movement of saidplunger, said armature being spaced from the Wall of the switch vesselbut disposed closer thereto than the lower part of said plunger whichenters said rst. body of conducting liquid, the space between the latterand said Wall being made large enough to avoid the setting up of undueresistance t0 movement of said plunger.

l2. An electric switch comprising a vessel containing a body ofconducting liquid, a tubular plunger in said vessel containing aconducting liquid and movable in the direction of its longitudinal axis,said plunger having an opening near the lower end thereof, an electrodepassing through the wall of the vessel into said first body 0fconducting liquid, a second electrode passing through the wall of thevessel into said second body of conducting liquid, magnetic means foractuating said plunger to vary the extent of immersion in said firstbody of conducting liquid selectively to establish and break electricalcontact between said electrodes by the mergence and separation of saidbodies of conducting liquid, respectively, at said opening, and aplurality of guiding means disposed at points spaced longitudinally inthe direction of movement of said plunger within said vessel for guidingsaid plunger clear of the wall of said vessel, said guiding meanscomprising said second electrode extending into said plunger and dippinginto said conducting liquid therein, and at least one constrictionformed on said plunger adapted to slide on said last-mentioned electrodeas the plunger moves, said one or more constrictions being so disposedthat they do not slide on t0 the part of the electrode which liesopposite said opening when the plunger is in the position in whichelectrical contact is broken.

ALFREDO CIAN CHI.

